Cheshire SSSIs and underlain by millstone grit and shale, they contain a variety of upland habitats, predominantly heather moorland, grassland and blanket mire. Ten SSSIs are located in Warrington and the former boroughs of Halton and Ellesmere Port & Neston, in the north-west of the county. These fall within the Urban Mersey Basin natural area, which also covers Greater Manchester and Merseyside. Although the area as a whole is one of the most densely populated regions in Europe, much of the area within Cheshire is farmland. Semi-natural habitats here include ancient woodland, raised bog and freshwater wetland. The Rixton Clay Pits site represents former industrial land, and railway cuttings expose geological features. Finally, the Liverpool Bay coastal region contains two estuaries, the Mersey and Dee, which are Cheshire's largest SSSIs. Sites Notes All tabulated data are sourced from the Natural England website, and were last updated on 1 March 2010. Data rounded to one decimal place. Area in acres converted from hectare value. Grid reference is based on the British national grid reference system, also known as OSGB36, and is the system used by the Ordnance Survey. Link to maps using the Nature on the Map service provided by Natural England. Natural England citation sheets for each SSSI. The River Dane and Holly Banks SSSIs overlap. References Cheshire Sites of Special